1. Plasmonic Imaging for Optical Lithography X-ray Wavelengths at Optical Frequencies Experiments: Progress and Plans Yunping Yang Josh Conway Eli Yablonovitch

2. The Problem Classically the resolution limit is determined by the Rayleigh Criterion: Various schemes have been developed to push this to finer resolution than the wavelength itself, but the scale will always be set by wavelength

3. Constant Energy Curves By adiabatically tapering the thin film thickness, very small (<50nm) plasmon wavelengths are attainable for in plane imaging. 1.5 eV 2.0 eV 2.5 eV 0 100 200 300 2040 400 6080 Plasmon Wavelength in nm Silver Film Thickness in nm Silver Film on Sapphire t p

4. t=1nm t=20nm t=5nm t=2nm 00.1 0.2 0.3 0.40.5 0 1 2 3 4 200100 50 20 15 30 40 10 0.6 Plasmon Wavelength in nm Plasmon Wave-Vector (2  /wavelength in nm) Plasmon Energy in eV h k t=thickness of metal film Optical frequencies, but with X-ray wavelengths! Dispersion Relation: Constant Thickness Curves

5. Grating Coupler Silver Glass Grating Design and fabricate gratings to maximize the coupling efficiency; Verify the DR with constant thickness; Find some material parameters

6. Launching of Surface Plasmons: ATR Coupler

7. Optical Setup for ATR Coupler Laser /2 PBS Beam Expander Iris Mirror Detector Lens 4f Sapphire Hemisphere Ag Thin Film

8. Optical Setup for ATR Coupler Characterize thin film, such as roughness, thickness; Experimentally verify the dispersion relation; Launching a standing wave for Plasmon Wavelength Measurement

9. A Possible Solution This permits X-ray wavelengths at optical frequencies

10. Plasmon Wavelength Measurement Antonello Nesci, Rene Dandliker, Hans Peter Herzig, “Quantitative amplitude and phase measurement by use of a heterodyne scanning near-field optical microscope,” Optics Letters, Volume 26, Issue 4, 208-210. Resolution: 1.6 nm

11. Taper Motivation dimple lens out-coupling slot far-field from conventional lens taper Taper design will be a trade between absorption (joule heating), scattering (an adiabatic profile), and maintaining a high enough effective index at all points of propagation to maintain features n 9 > n 8 >        >n 1 >n 0

12. Criteria Loss/ Wavelength (nm) It is clear that Loss/ becomes prohibitively large at short wavelengths Thus we change are adiabatic criteria accordingly  / = constant

13. Length (nm) Silver Film Thickness (nm) 100200300400500600 10 20 30 40 50 60 Taper Profile